The economist Richard Murphy says of “austerity”:
The result has been a myth about money that is now being used to oppress people. That myth suggests that governments do not have money, and that they only use taxpayer-generated funds. It also claims that this means that the money in question must be restricted in use. And it suggests governments must copy the characteristics of households, with whom they have literally nothing in common because governments can create money which households can't, and so limit the amount of money that they might put into use.
www.taxresearch.org.uk/Blog/
In other words governments can create money to invest in the economy. More money for the NHS would create more secure well paid jobs, meaning these workers can then afford to spend more thus creating more demand for goods and services, ultimately creating more jobs. Investment in building new houses creates jobs, demand for building materials to be manufactured and then those workers create more demand for goods and services etc.
The same could happen in social care, road maintenance (those damned potholes), libraries, Sure Start nurseries, schools, fire services, police forces and so on.
The extra income and spending means much higher tax receipts coming back to the government. A small amount of investment can go a long way. Win, win!